Pilot stem



E; A. HALL' PILOT STEM Feb. 25, 1930.

Filed Jan. 9, 1928 .1.. .my F

lill Il ua mw Patented Feb. 25, 19304 UNITED STATES PATENT OFFICE f ERNEST A. HALL, OF TOLEDO, OHIO, ASSIGNOR TO THE HALL MANUFACTURING COM- I' PANY, F TOLEDO, OHIO, A CORPORATION 0F OHIO :PILOT 'strain Application led January 9, 1928. Serial No. 245,369.

VThis invention relates to a pilot stem, ofA

improved construction, Aadapted to be used in connection with valve seat grinders and other tools which operate in a similar manner.

The object of the invention is to provide,

for the purpose stated, a pilot stem or spindle which is so constructed that it may be easily and firmly secured in a valve stem guideway, and in connection therewith, to

provide improved means for adjusting and centering the lower end portion of the stem within the guideway.

I, 'In using pilot stems, as heretofore commonly constructed, for thepurpose of centering valve seat grinders and the like, it has been necessary to secure the pilot stem in proper position by applying a centering nut,

expanding screw or equivalent means to the lower end of the stem after it has been inserted in the valve rod guidewa With the -present invention, the entire pi ot stem and adjusting means may be inserted through the upper end of the guideway, and after it'has been inserted, the lower end maybe easily adjusted so that' it will be centered with respect to the guideway and held securely in that position.

The specific construction of the invention and the advantages resulting therefrom will 30 be more particularlydescribed in connectionV with the accompanying drawing'in which- Figure 1 is a vertical section taken centrally through thelower part of thevalve seat grinding tool and the adjacent portion of the motor, with the pilot stem secured lin operative position. i l Fig. 2 is an enlarged central .vertical section through the lower part of the pilot stem, the section being taken substantially on the line 2-2 of Figure 3.

Fig. 3 is a horizontal section taken substantially on the line 3-'3 of Fig.' 2."

Fig. 4 is a vertical Section through the lower end of the upper section of the pilot stem, .showing a lmodified construction.

The internal combustion motor, a fragment of which is shown at 5, is formed with a cav-y ity 6 which may represent either the inlet or 50 exhaust, and which is formed with a valve |seat 7 Beneath the cavity 6 is a guideway .ceive the correspondingly threaded sleeve 15 formed at the upper end of the lower section 16. The end of the reduced portion 14 is formed with a central bore 17 which is reamed out to provide a conical seat 18 adapted to receive a steel ball 19. The upper portion of the section 16 is provided with a central bore 2O in which a plunger 21 is guided. 'An expansile coil spring 22, seated in the end of the bore 20, holds the plunger 21 normally in engagement with the ball 19. The section 16 is formed near the base of the sleeve 15 with a plurality of equally spaced openings 23 extending from the bore 2O through the lateral surface of the stem. The interior 4surfaces of these openings form seats to receive steel lballs24 which are adapted to project outwardly through the openings, but the outer edges of the openings are suiciently restricted to prevent the balls 24 from passing through the same. The reduced upper end of the plunger holds the balls 24 in their seats when the two sections of the pilot stem are being assembled.'

The stem 13 is alsoformed with a gradually tapered vconical enlargement 25, the base of which is somewhat larger than the internal diameter of the guideway. The normalv distance from the tapered enlargement 25 to tle'fballs 24is somewhat less than the length of the guideway 8.

` In order to insert the pilot stem in the valve rod guideway 8, the section 16 is uni screwed sufficiently to permit the balls 24 toA be moved inwardly toward lthe central cavity 20, thus permitting the pilot. stem to be inserted from the upper end of the guidewaywithout disassembling the same. When 100 the pilot stem is thus inserted, it is forced downwardly until the tapered enlargement 25 is rmly seated in the upper end of the 'guideway 8. In order tofacilitate the insertion and adjustment of the pilot stem, the latter is formed near its upper and lower ends' with transverse holes 26 and 27 respectively, for receiving cross rods.

After -inserting the pilot stem in the guideway, it is not -necessary to attach any nut, screw or the like to its lower end. All that it is necessary to do is to tighten the lower section by hand or by means of a cross rod inserted through the hole 27. The balls 18 and 24 automatically eifect the centering of the lower end of the stem as itis tightened They may be forced to exertr the greatest amount of pressure against the wall of the guideway, while offering comparatively little frictional resistance against the rotational movement which is necessary to tighten the same. The proportions of the tapered enlargement 25 and of theballs 19 and 24 are such that the pilot stem may be firmly secured in the guideway irrespective of how much the latter has been worn.

The modified construction shown n Fig. 4 is the same as the construction shown in the other figures with the exception that, instead of the central ball 19, a tapered pin 28 is set in a socket formed in the lower end of the upier section of the stem 13, and the lower en of this pin is in the shape .of a cone which constitutes an abutment for the balls 24.

When lthe grinding of the valve seat has -been completed the lower section 16 may be loosened suliiciently to permit the stem to be easily withdrawn from the guideway and to be inserted in like manner in the next valve stem guideway for grinding the next valve seat; f

While I have shown and Adescribed. cifically two forms in which the invention may be embodied, the principlesv of their operation are substantially the same. It ispb vious that the invention may be considerably modified in other respects without departing materially from the scpe thereof as claimed.

What I'claim is: e

1. A pilot stem for the purpose described, adaptedto have its lower end portion inserted in a valve stem guideway, said lower end portion having' a screw adjustment toward the upper end, and individuallyrotatable elements exerting increasing pressure against the wall of said guideway as said. lowerl end portion is thus adjusted.

2. A pilot stem for the purposel described,

- with its lower end portionhaving. a screw adjustment with respect to its upper end porj tion, said lower end portion 'being insertible downwardly through a valve stem guideway, individual rotatable elements carried by said stem, and means operable by the. screw adjustment, after the stem is inserted, to press said elements forcibly against the wall of said guideway.

3. A pilot stem adapted to be inserted in a valve stem guideway, said stem having upper. and lower sections with a screw threaded connection therebetween, said stem having a central cavity where the two sections meet, with openings from the central'cavity to the lateral surface of the stem, individual elements withinsaid openin s, and means for pressing 'said elements orcibly outwardly from said openings against the wall of said guideway.

4. A pilot stem adapted to be inserted in a valve stem guideway, said stem having upper and lower sections with a screw threaded connection therebetween, said stem having a central cavity where the two sections meet, with openings from the central cavity to the lateral surface of the stem, individual balls within the respective openings, said o enings being large enough to permit the alls to project therefrom but not to pass entirely therethrough, and means operable by a screw adjustment of the two sections toward each other, after the stem is inserted, to press said balls forcibly against the wall of said guide- Way'.

5. A pilot stem for the purpose described,

comprising an upper section with a reduced' threaded lower end, a lower section having at its upper end an internally threaded sleeve to receive the threaded end ofthe upper section, both sections being of less diameter than the valve stem guideway in which the pilot stem is to be used, said lower section having a central bore below said sleeve with openings from the bore through the lateral surface of the section, and means cooperating with said bore and openings to exert pressure against the wall of the ideway.

6. A pilot stem for t e purpose described,

comprising an upper section with a reduced threaded lower end presenting a centrally disposed abutment, a lower sectlon having at its upper end an internally threaded'sleeve to receive the threaded end of the upper section,

and freely rotatable means cooperating with said abutment and the lower sectionto exert pressure against the wall of the valve stem guideway when the two sections are adjusted toward each other.

-. 7. l-Apilot stem adapted to be inserted in a valve stem guideway, said stem comprising an upper sectionwith a reduced threaded lowerv end, a lower section having at its upper end an internally threaded sleeve to receive the threaded end of the upper section,

said lower section having a centralbore below -said seat,`with opemngs from said bore through the lateral surface of the section, a spring pressed plunger in said bore, balls held 1n said openings, and a centrally disposed abutment at the lower end of the upper section and normally engaged by the plunger, said abutment bein engageable with said balls to press them orcibly against the wall of said guideway, when the two sections are adjusted toward each other.

8. A pilot stem comprising two sections disposed in end to end relation with a screw threaded connection between them, said stem having a central cavity where the two ends are connected, and openings from said cavity through the lateral surface of one of said sections, a seat formedin the end of the other of said sections, and means coacting with said seat and said balls to positively force the latter to project outwardly from said openings, when the two sections of the stem are adjusted toward each other.

In testimony whereof, I have hereunto signed my name to this s ecification.

ER EST A. HALL.

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